BobbyFK, do you ever go to Dutch Bros? They have Birthday Cake drinks. You can either get in in a hot latte or as a milkshake. The milkshakes don't contain coffee so it would be good for your kid.
Here's a description of the milkshake:
The Birthday Cake blends the decadent flavors of Almond Roca and white chocolate. First, almond Roca syrup is blended with creamy white chocolate sauce and premium vanilla ice cream, then topped with whipped cream and multi-colored sprinkles.
Try it out and let us know what you think!